World War I involved 32 nations from 1914 to 1919. It redrew the world map and reshaped many borders in Europe. The collapse of the Russian Empire created Poland, the Baltics, and Finland.

The past 100 years have seen another world war and the rise and fall of the Soviet Union, but much of present-day Europe is based on the lines drawn following the conflict sparked by Princip's bullet.

Thirty-two years on from the fall of the Berlin Wall, there are now 1,800km of walls and fences either built or under construction on Europe’s borders. That is the equivalent of almost 12 new ...